PlanetPhysics/X Ray Microscope

An X-ray microscope, or X-ray tomograph uses electromagnetic radiation in the soft (long wavelength) X-ray region to produce images of tiny objects, such as living cells. Sir Lawrence Bragg produced some of the first usable X-ray images with his apparatus in the late 1940's. Early X-ray microscopes that were built by Paul Kirkpatrick and Albert Baez used grazing-incidence reflective `optics' to focus the X-rays, which grazed X-rays off parabolic, curved mirrors at a very high angle of incidence, in order to avoid total absorption and scattering of the X-ray beam.

At the Advanced Light Source (ALS)in Berkeley, CA, ($$http://ncxt.lbl.gov$$) the X-ray microscope model XM-1 is a complete field soft X-ray microscope operated by the Center for X-ray Optics which is dedicated to various applications in materials sciences and biology, nanoscience, (such as nanomagnetic materials) and environmental sciences. XM-1 utilizes an X-ray `lens' to focus X-rays on a CCD, in a manner superficially similar to an optical or electron microscope. Unlike the latter two types of earlier microscopes, however, the X-ray beam of long wavelengths is diffracted in the XM-1 by Fresnel zone plates down to 15nm and is thus able to combine moderately high spatial resolution with a sub-100ps time resolution to study ultrafast spin dynamics or fast kinetics. Its successor at ALS ($$http://www.cxro.lbl.gov/BL612/$$), XM-2, is capable of producing 3-dimensional (3D) tomograms of a single cell. A resolution of 30 nanometer is possible uwith XM-2 using the Fresnel zone plate `lens' which forms the reconstructed, highly-magnified image using the soft x-rays emitted from a synchrotron. Recently, the use of soft x-rays emitted from laser-produced plasmas rather than synchrotron radiation is becoming more popular.